shunt resistance

(noun)

a small resistance R placed in parallel with a galvanometer G to produce an ammeter; the larger the current to be measured, the smaller R must be; most of the current flowing through the meter is shunted through R to protect the galvanometer

Related Terms

Examples of shunt resistance in the following topics:

  • Voltmeters and Ammeters

    • The two crucial characteristics of any galvanometer are its resistance and its current sensitivity.
    • The total resistance must be:
    • For other voltage ranges, other resistances are placed in series with the galvanometer.
    • The same galvanometer can also function as an ammeter when it is placed in parallel with a small resistance R, often called the shunt resistance.
    • Since the shunt resistance is small, most of the current passes through it, allowing an ammeter to measure currents much greater than those that would produce a full-scale deflection of the galvanometer.

  • Biofilms and Disease

    • Biofilms, complex colonies of bacteria acting as a unit in their release of toxins, are highly resistant to antibiotics and host defense.
    • Once established, they are very difficult to destroy as they are highly resistant to antimicrobial treatments and host defense.
    • In healthcare environments, biofilms grow on hemodialysis machines, mechanical ventilators, shunts, and other medical equipment.
    • Once an infection by a biofilm is established, it is very difficult to eradicate because biofilms tend to be resistant to most of the methods used to control microbial growth, including antibiotics.
    • It has been said that they can resist up to 1,000 times the antibiotic concentrations used to kill the same bacteria when they are free-living or planktonic.

  • The Portacaval Shunt

    • Numerous studies have been conducted to examine the value of the portacaval shunt procedure, many using randomized controls.
    • A portacaval shunt is a treatment for high blood pressure in the liver.
    • Cirrhosis can be combatted by the portacaval shunt procedure, for which there have been numerous experimental trials using randomized assignment.

  • Dead Space: V/Q Mismatch

    • Anatomical dead space, or anatomical shunt, arises from an anatomical failure, while physiological dead space, or physiological shunt, arises from a functional impairment of the lung or arteries.
    • An example of an anatomical shunt is the effect of gravity on the lungs.
    • An anatomical shunt develops because the ventilation of the airways does not match the perfusion of the arteries surrounding those airways.
    • A physiological shunt can develop if there is infection or edema in the lung that obstructs an area.
    • A physiological shunt can develop if there is infection or edema in the lung which decreases ventilation, but does not affect perfusion; thus, the ventilation/perfusion ratio is affected.

  • Adjustments of the Infant at Birth

    • With the first breaths, there is a fall in pulmonary vascular resistance and an increase in the surface area available for gas exchange.
    • The higher blood oxygen content of blood within the aorta stimulates the constriction and ultimately the closure of this fetal circulatory shunt.

  • Capillaries

    • Secondly, capillary beds also consist of a vascular shunt which is a short vessel that directly connects the arteriole and venule at opposite ends of the bed, allowing for bypass.
    • This allows blood flow to increase while resistance decreases.

  • The Pentose Phosphate Shunt

    • The pentose phosphate pathway (PPP; also called the phosphogluconate pathway and the hexose monophosphate shunt) is a process that breaks down glucose-6-phosphate into NADPH and pentoses (5-carbon sugars) for use in downstream biological processes.
    • Outline the two major phases of the pentose phosphate shunt: oxidative and non-oxidative phases

  • Resistance and Resistivity

    • Resistance and resistivity describe the extent to which an object or material impedes the flow of electric current.
    • Conductance and resistance are reciprocals .
    • What determines resistivity?
    • Its resistance to the flow of current is similar to the resistance posed by a pipe to fluid flow.
    • Identify properties of the material that are described by the resistance and resistivity

  • Resistance to French Rule

  • Dependence of Resistance on Temperature

    • Resistivity and resistance depend on temperature with the dependence being linear for small temperature changes and nonlinear for large.
    • The resistivity of all materials depends on temperature.
    • where ρ0 is the original resistivity and α is the temperature coefficient of resistivity.
    • is the temperature dependence of the resistance of an object, where R0 is the original resistance and R is the resistance after a temperature change T.
    • Compare temperature dependence of resistivity and resistance for large and small temperature changes